CODEWITHSUNDEEP
c#attributes
turkinator
turkinator

Reputation: 925

C# Custom Attribute, Targets.Method WHERE returntype = type && IsStatic

So, I have a custom attribute that looks like this:

[AttributeUsage(System.AttributeTargets.Method, AllowMultiple = false)]
public class MyAttribute: System.Attribute
{
    private string name;
    public double version;

    public MyAttribute(string _name)
    {
        this.name = _name;
        version = 1.0;
    }
}

Is it possible to add the following conditions to this attribute:

Method.ReturnType = typeof(specificClass) 

Method.IsStatic

Also, how do I implement the following condition?

public static void Do(Func<type> func) where func : MyAttribute //make sure Func<type> is decorated with my attribute
{
    //do something with 'func'
}

Upvotes: 0

Views: 707

Answers (1)

Vadim Martynov
Vadim Martynov

Reputation: 8892

No, it is not. AttributeUsage determines how a custom attribute class can be used.

The first AttributeUsage argument (ValidOn) must be one or more elements of the AttributeTargets enumeration. Multiple target types can be linked together with the OR operator, like this:

[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field)]
class NewPropertyOrFieldAttribute : Attribute { }

If the AllowMultiple argument is set to true, then the resulting attribute can be applied more than once to a single entity, like this:

[AttributeUsage(AttributeTargets.Class, AllowMultiple = true)]
class MultiUseAttr : Attribute { }

[MultiUseAttr]
[MultiUseAttr]
class Class1 { }

[MultiUseAttr, MultiUseAttr]
class Class2 { }

If Inherited is set to false, then the attribute is not inherited by classes that are derived from a class that is attributed. For example:

[AttributeUsage(AttributeTargets.Class, Inherited = false)]
class Attr1 : Attribute { }

[Attr1]
class BClass { }

// In this case Attr1 is not applied to DClass via inheritance.
class DClass : BClass { }

That is all parameters that you can control for attribute usage in compile time. You can validate usage scenarios in the run-time via reflection but it's slow and error-prone way.

Upvotes: 1

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